Construction And Fabrication Of A Mobile Deep Freezer

This work on the construction and fabrication of a mobile deep freezer revolves around the concept of refrigeration. The concept of refrigeration revolves around the reverse Carnot cycle. This is a cycle involving isentropic expansion (at the throttling valve), isothermal expansion (at the evaporator), isentropic compression (at the compressor) and isothermal compressor ( at the condenser) Compression raises the temperatures of the refrigerant above that of its natural surrounding so that it can give up its heat in a heat exchanger to a heat sink such as air or water (condenser). Expansion lowers the refrigerant temperature below the temperature that is to be produced inside the cooling compartment.

TABLE OF CONTENTS

Cover page

Title page

Approval page

Dedication

Acknoweldgement

Abstract

CHAPTER ONE

1.0        introduction

1.1         background of the project

• Objective of the project
• Purpose of the project
• Project motivation
• Benefit of the project
• Importance of the project
• Application of the project

CHAPTER TWO

LITERATURE REVIEW

2.1         Review of related studies

CHAPTER THREE

DESIGN ANALYSIS AND CALCULATIONS

• Determination and choice of condenser and Evaporator temperature.
• Cooling Load Calculation
• Flow Rate
  • Mass flow rate
  • Ton of Refrigeration
  • Volume flow rate
• Determination of Compressor size
• Determination of pipe size and length
  • Comparing the velocities for different pipe size.
  • Summary table.

CHAPTER FOUR: CONSTRUCTION DETAILS

• Material Selection
• Sequence of operation
• Assembly
• Maintenance and use Instructions
  • Condenser Maintenance
  • Defrosting
  • Other Instructions
  • Common Complaints, Causes and Remedy
• Refrigerants

4.6        Requirements for refrigerants

• Identifying Refrigerants by number
• Halide refrigerants
• Grouping and Classification of refrigerants
• Group one Refrigerants
• R-12 Dichlorodi Fluoromethane (ccl₂f₂)
• R-22 Monochlorodi fluoromethane (CHCLF₂)
• R-11 Trichloromono fluoromethane (CCL₃F)
• Azeotropic Mixtures
• R-500 Refrigerant
• R-502 Refrigerant (R-22 + R-115) (CHCLF₂/CCLF₂ CF₃)
• R-503 Refrigerant (R-23 +R-13) (CHF₃/CCLF₃).
• R-504 Refrigerant (R-32 +R115) (CH₂F₂ (F₃ CCLF₂)
• Group two refrigerants
• R- 717 Ammonia (NH3)
• Group three refrigerants
• Expendable Refrigerants
• Water as a Refrigerants
• Refrigerant Cylinders
• Color code for refrigerants cylinders
• Cost Analysis

CHAPTER FIVE

5.1        Recommendation

5.2        Conclusion

5.3       Reference

 

LIST OF SYMBOLS

M                    =          Mass

A                     =          Area

V                     =          Volume

L                      =          Length

W                    =          Width

H                     =          Height

S                      =          Entropy

M                     =          Mass flow rate

G                     =          Gravity

E                      =          Density

D                     =          Diameter

E                      =          Enthalpy

Hf                    =          Latent heat of fusion

U                     =          Internal energy

T                      =          Temperature difference

T                      =          Temperature

H.P                  =          Horse power

K                     =          Thickness of Materials

Vo                   =          Swept volume

Cop                 =          Coefficient of performance

C                     =          Specific heat

AC                  =          Alternating current

 

CHAPTER ONE

1.0                                                           INTRODUCTION

The main objective of this project is to construct and fabricate a deep freezer. The purpose of a deep freezer is to extract as mush heat from the cold body as possible with the expenditure of as little work as possible. In the refrigeration cycle, a substance called the refrigerant is compressed, cooled and then expanded. In expanding the refrigerant absorbs heat its surrounding (the cooling compartment) to provide refrigeration. After the refrigerant absorbs heat from the source, the cycle is repeated.

The second chapter of these write-up ushers in a precise review of the history and literature of refrigeration from ancient man to modern day or contemporary man (i.e modern refrigerating equipment).

Chapter three deals in detail on the methods of calculating refrigeration equipment. Chapter four sequentially gives the overview of the factors, qualities and properties considered in choice decision of the material components (both standard/ranging engineering materials) used for the fabrication and the steps undergone in the assembly of the components to form the refrigerating equipment.

The fifth chapter analysis the material and labour cost incurred in the course of undertaking this project. Chapter six, summarily is a low down of the maintenance and use instructions to be strictly adhered to in order to make the most effective, economic and efficient use of the refrigerating equipment as well as enable the equipment complete its service life. There is also a provision in this part for the notification of the usual defects observed or experienced during use and the corresponding panacea for them. Included is the reference for future consultancy which helps the student or reader who decides to embark on further research or a fact finding mission on innovations that may add as a filling to this work or to the topic as a whole.

This write-up within its scope is moderate sufficient to the educate the reader on the design and fabrication of a deep freezer.

1.2                                              BACKGROUND OF THE PROJECT

Firstly refrigeration in the process of removing  heat from a substance or  space in order to make it cooler.

A mobile deep freezer is not different from  all  other refrigeration the only difference is that it can be moved easily by wheel or rollers to different places in a given time with less force applied to effect the movement.

In refrigeration the three mode   of heat transfer is employed causing heat to flow from high temperature regions to low temperature regions.  The   substance used to carry heat in the refrigeration is known as the refrigerant.

Refrigerant is the cooling agent in refrigeration.  It makes indirect contact with the substance to be  cooled.  It  is circulated in the  refrigeration  circuit  and  the attendant change of state  from liquid to vapour brings about the  necessary  cooling  that is  required in the system which also involves  INTENT OR SENSIBLE HEAT.

Refrigeration is accompanied by various method such as the vapour compression system absorption system and steam jet refrigeration cycle.

Refrigeration contributes greatly to the raising of living standards of people its uses can not be over emphasized in this book.  The most common used and one that is readily recognized is the preservation of food.  Most products in our homes businesses industries laboratories  hospitals  farms etc are affected by refrigeration.

Its application is also extended to other areas  apart  from  food in medicine it is used in blood banks for antibiotic  for  making ice  for compression and low  temperature  surgery for presenting certain tissues that pathologist work on. It is very essential in genetic    engineering  to preserve sperms and eggs or longer years before they work on them  to bring life.

Deep freezer is an Electro- mechanical appliance which maintains the temperature of substance space or material as requires by the user it produces artificial cooling.  It operates on the principal of reversed cannot cycle that is to say that it absorbs heat from a low temperature and rejects it to a high temperature region.

The compressor provides the conversion of energy that is used in circulating the refrigerant round the circuit.

The crankshaft drives the piston through the connecting rod and it’s moved by the tongue produced by electric motor.  The pumping effect of the piston produces the high pressure on the refrigerant which sets it in motion.  In the causes of circulation and attendant change of state the refrigerant returns to the initial state and ready for another cycle.

In a deep freezer the condenser performs function similar to that of the radiator in an auto mobile.  It cools the hot refrigerator gas by giving out hear to the dryer which traps moisture that can block the metering device.  The liquid refrigerant passes through the metering device which expands the liquid into the evaporator pipe which is of  large  cross sectional area.

The pipe is laid on the  inside of the deep freezer. A lot of insulation is done to isolate the refrigerated space from the surrounding its heating effect.

1.2                                                      AIM OF THE PROJECT

The main aim of this project is to construct and fabricate a deep freezer.

1.3                                    OBJECTIVE AND PURPOSE OF THE PROJECT

The objectives and purpose of the project is to achieve the following viz:

1. To design and construct portable domestic cooling equipment that would improve on existing design taken into consideration.
2. To design and construct a cooling system that is efficient with little or no complexity in maintenance.
3. To design and construct cooling equipment that is economical, with a reduced height.
4. To design and construct  a cooling equipment  that will be mobile economical and cost that  a common man can afford.

1.4                                                     PROJECT MOTIVATION

Looking into the present situation of things the menace  caused by road side craftsmen who tends to spoil other  progress  in pretence to repairing  or constructing of deep freezer so that they will enrich their  pocket and then gives out fake freezers that will last for few months we then decided to embark on this project.

 

1.5                                               IMPORTANCE OF THE PROJECT

The project is designed to accomplish a fast freezing system without destruction of bottles at very low temperature it is designed in such a way that the freshness and nutrient of food material is refined.

It  is based on reduced weight cost fast freezing techniques compactness longer life span also to improve on existing designs.

1.6                                                 BENEFIT OF CTHE PROJECT

Road side craftsmen that enrich their  pockets instead of  satisfying the consumers will be eliminated food stuff can be preserved   for a very long time.

1.7                                              APPLICATION OF THE PROJECT

The application of the refrigeration principle is limitless. The most common used and one that is readily recognized is the preservation of food. Almost all products in the home, on form in industries of in the laboratories are in some ways affected by refrigeration. Thus refrigeration has become an essential commodity in modern living as no family will afford to miss it.

CHAPTER TWO

LITERATURE REVIEW

While it is only in recent years that refrigeration equipment has been mass-produced and widely used, its benefits will have been apparent to ancient man. The value of ice as a preservative was known and put to use thousands of years ago. In winter it was cut and moved into ice house which were built into the ground to make use of the insulating properties of social. Such a structure was described a Chinese poet, Shih ching about three thousand years ago. In the middle East and India, water was chilled by evaporating it through porous day pots which were buried overnight in favourable condition it could be made cold enough to form ice. The Indian Sub-continent also saw the first moves towards air conditioning…